import fecha from 'static/element-ui/src/utils/date';
import {t} from 'static/element-ui/src/locale';

const weeks = ['sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat'];
const months = ['jan', 'feb', 'mar', 'apr', 'may', 'jun', 'jul', 'aug', 'sep', 'oct', 'nov', 'dec'];

const newArray = function (start, end) {
    let result = [];
    for (let i = start; i <= end; i++) {
        result.push(i);
    }
    return result;
};

export const getI18nSettings = () => {
    return {
        dayNamesShort: weeks.map(week => t(`el.datepicker.weeks.${week}`)),
        dayNames: weeks.map(week => t(`el.datepicker.weeks.${week}`)),
        monthNamesShort: months.map(month => t(`el.datepicker.months.${month}`)),
        monthNames: months.map((month, index) => t(`el.datepicker.month${index + 1}`)),
        amPm: ['am', 'pm']
    };
};

export const toDate = function (date) {
    return isDate(date) ? new Date(date) : null;
};

export const isDate = function (date) {
    if (date === null || date === undefined) return false;
    if (isNaN(new Date(date).getTime())) return false;
    if (Array.isArray(date)) return false; // deal with `new Date([ new Date() ]) -> new Date()`
    return true;
};

export const isDateObject = function (val) {
    return val instanceof Date;
};

export const formatDate = function (date, format) {
    date = toDate(date);
    if (!date) return '';
    return fecha.format(date, format || 'yyyy-MM-dd', getI18nSettings());
};

export const parseDate = function (string, format) {
    return fecha.parse(string, format || 'yyyy-MM-dd', getI18nSettings());
};

export const getDayCountOfMonth = function (year, month) {
    if (month === 3 || month === 5 || month === 8 || month === 10) {
        return 30;
    }

    if (month === 1) {
        if (year % 4 === 0 && year % 100 !== 0 || year % 400 === 0) {
            return 29;
        } else {
            return 28;
        }
    }

    return 31;
};

export const getDayCountOfYear = function (year) {
    const isLeapYear = year % 400 === 0 || (year % 100 !== 0 && year % 4 === 0);
    return isLeapYear ? 366 : 365;
};

export const getFirstDayOfMonth = function (date) {
    const temp = new Date(date.getTime());
    temp.setDate(1);
    return temp.getDay();
};

// see: https://stackoverflow.com/questions/3674539/incrementing-a-date-in-javascript
// {prev, next} Date should work for Daylight Saving Time
// Adding 24 * 60 * 60 * 1000 does not work in the above scenario
export const prevDate = function (date, amount = 1) {
    return new Date(date.getFullYear(), date.getMonth(), date.getDate() - amount);
};

export const nextDate = function (date, amount = 1) {
    return new Date(date.getFullYear(), date.getMonth(), date.getDate() + amount);
};

export const getStartDateOfMonth = function (year, month) {
    const result = new Date(year, month, 1);
    const day = result.getDay();

    if (day === 0) {
        return prevDate(result, 7);
    } else {
        return prevDate(result, day);
    }
};

export const getWeekNumber = function (src) {
    if (!isDate(src)) return null;
    const date = new Date(src.getTime());
    date.setHours(0, 0, 0, 0);
    // Thursday in current week decides the year.
    date.setDate(date.getDate() + 3 - (date.getDay() + 6) % 7);
    // January 4 is always in week 1.
    const week1 = new Date(date.getFullYear(), 0, 4);
    // Adjust to Thursday in week 1 and count number of weeks from date to week 1.
    // Rounding should be fine for Daylight Saving Time. Its shift should never be more than 12 hours.
    return 1 + Math.round(((date.getTime() - week1.getTime()) / 86400000 - 3 + (week1.getDay() + 6) % 7) / 7);
};

export const getRangeHours = function (ranges) {
    const hours = [];
    let disabledHours = [];

    (ranges || []).forEach(range => {
        const value = range.map(date => date.getHours());

        disabledHours = disabledHours.concat(newArray(value[0], value[1]));
    });

    if (disabledHours.length) {
        for (let i = 0; i < 24; i++) {
            hours[i] = disabledHours.indexOf(i) === -1;
        }
    } else {
        for (let i = 0; i < 24; i++) {
            hours[i] = false;
        }
    }

    return hours;
};

export const getPrevMonthLastDays = (date, amount) => {
    if (amount <= 0) return [];
    const temp = new Date(date.getTime());
    temp.setDate(0);
    const lastDay = temp.getDate();
    return range(amount).map((_, index) => lastDay - (amount - index - 1));
};

export const getMonthDays = (date) => {
    const temp = new Date(date.getFullYear(), date.getMonth() + 1, 0);
    const days = temp.getDate();
    return range(days).map((_, index) => index + 1);
};

function setRangeData(arr, start, end, value) {
    for (let i = start; i < end; i++) {
        arr[i] = value;
    }
}

export const getRangeMinutes = function (ranges, hour) {
    const minutes = new Array(60);

    if (ranges.length > 0) {
        ranges.forEach(range => {
            const start = range[0];
            const end = range[1];
            const startHour = start.getHours();
            const startMinute = start.getMinutes();
            const endHour = end.getHours();
            const endMinute = end.getMinutes();
            if (startHour === hour && endHour !== hour) {
                setRangeData(minutes, startMinute, 60, true);
            } else if (startHour === hour && endHour === hour) {
                setRangeData(minutes, startMinute, endMinute + 1, true);
            } else if (startHour !== hour && endHour === hour) {
                setRangeData(minutes, 0, endMinute + 1, true);
            } else if (startHour < hour && endHour > hour) {
                setRangeData(minutes, 0, 60, true);
            }
        });
    } else {
        setRangeData(minutes, 0, 60, true);
    }
    return minutes;
};

export const range = function (n) {
    // see https://stackoverflow.com/questions/3746725/create-a-javascript-array-containing-1-n
    return Array.apply(null, {length: n}).map((_, n) => n);
};

export const modifyDate = function (date, y, m, d) {
    return new Date(y, m, d, date.getHours(), date.getMinutes(), date.getSeconds(), date.getMilliseconds());
};

export const modifyTime = function (date, h, m, s) {
    return new Date(date.getFullYear(), date.getMonth(), date.getDate(), h, m, s, date.getMilliseconds());
};

export const modifyWithTimeString = (date, time) => {
    if (date == null || !time) {
        return date;
    }
    time = parseDate(time, 'HH:mm:ss');
    return modifyTime(date, time.getHours(), time.getMinutes(), time.getSeconds());
};

export const clearTime = function (date) {
    return new Date(date.getFullYear(), date.getMonth(), date.getDate());
};

export const clearMilliseconds = function (date) {
    return new Date(date.getFullYear(), date.getMonth(), date.getDate(), date.getHours(), date.getMinutes(), date.getSeconds(), 0);
};

export const limitTimeRange = function (date, ranges, format = 'HH:mm:ss') {
    // TODO: refactory a more elegant solution
    if (ranges.length === 0) return date;
    const normalizeDate = date => fecha.parse(fecha.format(date, format), format);
    const ndate = normalizeDate(date);
    const nranges = ranges.map(range => range.map(normalizeDate));
    if (nranges.some(nrange => ndate >= nrange[0] && ndate <= nrange[1])) return date;

    let minDate = nranges[0][0];
    let maxDate = nranges[0][0];

    nranges.forEach(nrange => {
        minDate = new Date(Math.min(nrange[0], minDate));
        maxDate = new Date(Math.max(nrange[1], minDate));
    });

    const ret = ndate < minDate ? minDate : maxDate;
    // preserve Year/Month/Date
    return modifyDate(
        ret,
        date.getFullYear(),
        date.getMonth(),
        date.getDate()
    );
};

export const timeWithinRange = function (date, selectableRange, format) {
    const limitedDate = limitTimeRange(date, selectableRange, format);
    return limitedDate.getTime() === date.getTime();
};

export const changeYearMonthAndClampDate = function (date, year, month) {
    // clamp date to the number of days in `year`, `month`
    // eg: (2010-1-31, 2010, 2) => 2010-2-28
    const monthDate = Math.min(date.getDate(), getDayCountOfMonth(year, month));
    return modifyDate(date, year, month, monthDate);
};

export const prevMonth = function (date) {
    const year = date.getFullYear();
    const month = date.getMonth();
    return month === 0
        ? changeYearMonthAndClampDate(date, year - 1, 11)
        : changeYearMonthAndClampDate(date, year, month - 1);
};

export const nextMonth = function (date) {
    const year = date.getFullYear();
    const month = date.getMonth();
    return month === 11
        ? changeYearMonthAndClampDate(date, year + 1, 0)
        : changeYearMonthAndClampDate(date, year, month + 1);
};

export const prevYear = function (date, amount = 1) {
    const year = date.getFullYear();
    const month = date.getMonth();
    return changeYearMonthAndClampDate(date, year - amount, month);
};

export const nextYear = function (date, amount = 1) {
    const year = date.getFullYear();
    const month = date.getMonth();
    return changeYearMonthAndClampDate(date, year + amount, month);
};

export const extractDateFormat = function (format) {
    return format
        .replace(/\W?m{1,2}|\W?ZZ/g, '')
        .replace(/\W?h{1,2}|\W?s{1,3}|\W?a/gi, '')
        .trim();
};

export const extractTimeFormat = function (format) {
    return format
        .replace(/\W?D{1,2}|\W?Do|\W?d{1,4}|\W?M{1,4}|\W?y{2,4}/g, '')
        .trim();
};

export const validateRangeInOneMonth = function (start, end) {
    return (start.getMonth() === end.getMonth()) && (start.getFullYear() === end.getFullYear());
};
